Unconventional superconductivity in Nd<sub>1-x</sub>Eu<sub>x</sub>NiO<sub>2</sub> thin films

ORAL

Abstract

The infinite-layer nickelates present a new class of superconductors that have intriguing similarities to the copper-based high Tc superconductors, providing a platform to study unconventional superconductivity. We investigate the upper critical magnetic field and superconducting gap of superconducting Nd1-xEuxNiO2 (NENO) thin films with x=0.2 to 0.35, synthesized using Al reduction technique.1 Magnetoresistance measurements reveal magnetic field enhanced superconductivity, which is the result of interaction between magnetic Eu ions and superconducting states in the Ni dx2-y2 orbital. The upper critical magnetic fields, Hc2, for in-plane and out-of-plane magnetic fields are anisotropic and violate the weak-coupling Pauli limit Hc2,P=1.86Tc. Terahertz spectroscopy confirms a large gap-to-Tc ratio 2∆/kBTc, consistent with the Pauli limit violation. We interpret these results as evidence of strong electron-electron coupling and a large superconducting energy gap of NENO.



[1] Wei, W., Vu, D., et al. Sci Adv 9, 27 (2023).

*This work was supported by U.S. Department of Energy, under award number DE-SC0019211.A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by NSF Cooperative Agreement No. DMR-2128556 and the State of Florida.

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Presenters

  • Dung D Vu

    • Yale University

Authors

  • Dung D Vu

    • Yale University

  • Hangoo Lee

    • Max Planck Institute for the Structure and Dynamics of Matter

  • Zheting Jin

    • Yale University

  • Dmitry V Chichinadze

    • National High Magnetic Field Laboratory

  • Daniele Nicoletti

    • Max Planck Institute for the Structure and Dynamics of Matter

  • Michele Buzzi

    • Max Planck Institute for the Structure and Dynamics of Matter

  • Wenzheng Wei

    • Yale University

  • Boris A Maiorov

    • Los Alamos National Laboratory (LANL)
    • Los Alamos National Laboratory

  • Christopher A Mizzi

    • Los Alamos National Laboratory (LANL)
    • Los Alamos National Laboratory

  • Alexey Suslov

    • National High Magnetic Field Laboratory

  • Cyprian K Lewandowski

    • National High Magnetic Field Laboratory
    • Florida State University

  • Sohrab Ismail-Beigi

    • Yale University

  • Frederick J Walker

    • Yale University

  • Andrea Cavalleri

    • Max Planck Institute for the Structure & Dynamics of Matter

  • Charles H Ahn

    • Yale University